I am trying to work on the Molecular Clock activity for the Human Evolution Unit. In part 2, I am supposed to calibrate the clock of sequence divergence to known age, but the manual told me to put the sequence divergence on the X axis and the known age on the Y axis. A proper line graph should have the controlled data, in this case the known age, on the X axis. Am I correct in my belief or do they know something that I do not?